It was his subconscious which told him this - that infuriating part of a person's brain which never responds to interrogation, merely gives little meaningful nudges and then sits humming quietly to itself, saying nothing.

Earthmen are not proud of their ancestors and never invite them round to dinner.

There’s no point in acting surprised about it. All the planning charts and demolition orders have been on display at your local planning department in Alpha Centauri for 50 of your Earth years, so you’ve had plenty of time to lodge any formal complaint and it’s far too late to start making a fuss about it now... What do you mean you’ve never been to Alpha Centauri? Oh, for heaven’s sake, mankind, it’s only four light years away, you know. I’m sorry, but if you can’t be bothered to take an interest in local affairs, that’s your own lookout. Energize the demolition beams.

Let us be dreamers, thinkers, speculative philosophers, or as our spouses would have it: Idiots

Just believe everything I tell you, and it will all be very, very simple.' Ah, well, I'm not sure I believe that.

Time, we know, is relative. You can travel light years through the stars and back, and if you do it at the speed of light then, when you return, you may have aged mere seconds while your twin brother or sister will have aged twenty, thirty, forty or however many years it is, depending on how far you traveled. This will come to you as a profound shock, particularly if you didn't know you had a twin brother or sister.

Religion ... has certain ideas at the heart of it which we call sacred or holy or whatever. What it means is, 'Here is an idea or a notion that you're not allowed to say anything bad about; you're just not. Why not? Because you're just not. If someone votes for a party that you don't agree with, you're free to argue about it as much as you like; everybody will have an argument but nobody feels aggrieved by it. ... But on the other hand, if somebody says 'I mustn't move a light switch on a Saturday', you say 'I respect that'.